Platelet-rich plasma is being studied as a regenerative treatment option for erectile dysfunction, but it is unclear whether adding daily tadalafil gives additional benefit over platelet-rich plasma alone. This study evaluates adult men with mild to mild-moderate erectile dysfunction who had an inadequate response to previous phosphodiesterase type 5 inhibitor treatment.

Participants were randomly assigned to receive either intracavernosal platelet-rich plasma injections combined with oral tadalafil 5 milligrams once daily, or intracavernosal platelet-rich plasma injections alone. The platelet-rich plasma injection protocol consisted of three intracavernosal treatment sessions spaced two weeks apart. Erectile function was assessed using the International Index of Erectile Function-5 questionnaire at baseline and during follow-up at 1, 3, and 6 months. Penile duplex Doppler ultrasound was performed at baseline and after 6 months to assess erectile blood-flow parameters.

The study hypothesis is that adding daily tadalafil to intracavernosal platelet-rich plasma may produce greater improvement in patient-reported erectile function compared with platelet-rich plasma alone, while also allowing assessment of whether this improvement is accompanied by measurable changes in penile Doppler parameters. The study included 156 participants in the final analysis, with 78 participants in each treatment group.

Inclusion Criteria:

• Adult men aged 18 years or older.
• Diagnosis of mild to mild-moderate erectile dysfunction according to the International Index of Erectile Function-5.
• Inadequate response to previous phosphodiesterase type 5 inhibitor treatment.
• Eligible for intracavernosal platelet-rich plasma injection.
• Eligible for oral tadalafil treatment.
• Baseline penile duplex Doppler ultrasound assessment available.

Exclusion Criteria:

• Severe erectile dysfunction.
• Peyronie's disease.
• Previous major pelvic surgery.
• Previous pelvic trauma.
• Known bleeding or coagulation disorder.
• Contraindication to phosphodiesterase type 5 inhibitors, including nitrate therapy.
• Significant cardiac disease contraindicating tadalafil use.
• Total testosterone less than 300 nanograms per deciliter.
• Refusal or inability to provide written informed consent.

Deidentified individual participant data supporting the main study results may be shared upon reasonable request. Shared data may include baseline demographic and clinical characteristics, treatment allocation, International Index of Erectile Function-5 scores, and penile duplex Doppler ultrasound parameters. No directly identifying participant information will be shared.

Data will be available beginning 6 months after publication of the main study results and will remain available for 3 years.

Data will be shared with qualified researchers who submit a scientifically sound research proposal. Requests will be reviewed by the study investigators. Data will be provided only after approval of the request and, when required, completion of a data sharing agreement.